Footprints of ancient human ancestors appeared briefly at a Stone Age site on England’s southeastern coast. Before long, however, the sea eroded them away again. At least five individuals created the prints between 1 million and 780,000 years ago, scientists report.

The footprints were discovered and photographed in May 2013. Heavy seas had worn away layers of hardened silt at England’s Happisburgh site. Low tide then exposed the stretch of footprint-covered sediment, report archaeologist Nick...